SUMMARY OF THE BASIDIA FUNGI 271 



is indeed a four-celled filament resembling the promycelium of 

 a rust, each cell developing a spore at one side on a sterigmata. 

 The winter spores, or teleutospores, of the smuts and rusts are 

 considered to be special resting cells of the fungi, developed to 

 carry these parasitic forms over unfavorable seasons of cold or 

 drought when the host plants are not alive. There is thus a 

 break in the life history at the point where the basidium should 

 normally appear. The germination of these spores continues 

 the life history with the immediate development of a structure 

 (the promycelium) which corresponds to a basidium with its 

 spores. 



The higher basidia fungi have apparently lost all trace of 

 sexual organs, but the cluster-cup stage in the rusts is believed 

 to indicate the remains of a modified sexual generation in their 

 life histories. The evidence for this view rests chiefly upon the 

 behavior of the nuclei throughout the life history of the rust 

 and is too complicated for treatment here. The basidia fungi 

 are therefore chiefly, if not wholly, apogamous. The origin and 

 evolution of the Basidiomycetes is a problem as yet unsolved, 

 which cannot be here considered. The basidia fungi are, how- 

 ever, by far the most wonderfully varied and specialized assem- 

 blage of the fungi. 



